JPH06222229A - Optical waveguide element and its manufacture - Google Patents

Abstract

PURPOSE:To provide an optical waveguide element which is small in photoconductive loss, small in connection loss with optical fiber, and capable of integrating with the other optical elements and electric elements, and also provide its manufacturing method. CONSTITUTION:An optical waveguide element is provided with a dielectric substrate, a holding substrate 1 such as semiconductor substrate, glass substrate, etc., and a glass substrate 2 connected directly to the holding substrate 1, and an optical waveguide 3 is provided inside the glass substrate 2. Also the manufacturing method for it is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide device in which a glass optical waveguide is integrally formed on a dielectric or semiconductor substrate.

[0002]

2. Description of the Related Art Conventional optical waveguide devices include an optical waveguide functioning as a light transmission path, an optical modulator for changing the intensity and phase of light, an optical switch for switching light, and an optical waveguide for amplifying light intensity. Type optical amplifiers and optical phase matching elements are known. These conventional optical waveguide devices are described, for example, by R. Alferness in "Waveguide Electr
ooptic Modulators ", IEEE Transactions on Microwave
and Techniques, Vol.MTT-30, No.8, 1121-1137 (1982)
It is described in. These optical waveguide elements are formed on a dielectric substrate, a glass substrate or a semiconductor substrate.

For the conventional method of manufacturing an optical waveguide, see, for example, "Optical Waveguide Modula" by I. Kaminow.
tors ", IEEE Transactions on Microwave and Technique
s, Vol. MTT-23, No. 1, 57-70 (1975). For example, as a method of forming an optical waveguide on a dielectric, particularly a dielectric substrate having an electro-optical effect, a method of diffusing Ti into a lithium niobate substrate or the like and using the Ti diffusion portion as an optical waveguide, or a method of forming an optical waveguide on a lithium tantalate substrate A method of epitaxially growing a crystal of lithium niobate and using a crystal of lithium niobate as an optical waveguide, and a lithium niobate thin film is formed on a lithium niobate or lithium tantalate substrate by sputtering to form a lithium niobate thin film. The method of using an optical waveguide is described.

As a method for forming a glass or quartz optical waveguide on various substrates such as semiconductors, a method of forming a Si thermal oxide film on a Si semiconductor substrate and forming an optical waveguide on the Si thermal oxide film, or a glass And quartz materials are deposited on a Si substrate by various thin film technologies such as sputtering, vacuum deposition, various chemical vapor deposition methods, flame deposition methods, sol-gel methods, etc. Methods of forming waveguides are known.

For example, in Japanese Unexamined Patent Publication No. 1-189614, first, a layer (clad layer) such as glass having a refractive index lower than that of the optical waveguide portion is formed on a Si substrate by a flame deposition method. A layer (core part) made of glass or a quartz material having a refractive index higher than that of the clad layer is formed on top of it, and a layer with a low refractive index (clad layer) is further formed on it if necessary. Then, a configuration for controlling the confinement of light to the core portion is described. With such a structure, the light is almost confined in the core portion and can be used as an optical waveguide.

Regarding a structure having a glass optical waveguide on a glass substrate, for example, in USP 5,193,137, a quartz glass substrate is formed on a quartz glass substrate through a low-refractive index glass layer by a film forming technique. A structure having a core portion is described.

[0007]

An optical waveguide element in which an optical waveguide is formed by diffusion of Ti on a dielectric substrate having an electro-optical effect such as lithium niobate has a high response speed and can be easily electrically guided. It is applied to high-speed optical modulators, etc. However, since the shape, size, and refractive index of the connecting portion of the optical waveguide are greatly different from those of the optical fiber, there is a problem that the coupling loss with the optical fiber is large.

The glass-based optical waveguide device has an advantage that it is possible to reduce the connection loss with a normal silica-based optical fiber because the shape, size, and refractive index of the light emitting portion of the optical waveguide can be easily matched with those of the optical fiber. is there. But,
Since glass has no electro-optical effect, it cannot control light electrically. Therefore, a method of controlling light by utilizing the temperature change of the refractive index of glass is known, but there is a big problem that the response speed is decisively slower than that using the electro-optic effect.

Further, in a glass-based optical waveguide element in which an optical waveguide is formed by a method of making a difference in refractive index by diffusion of a metal element, the symmetry of the shape of the connecting portion of the optical waveguide becomes low, and the coupling loss with the optical fiber is reduced. It cannot be reduced. further,
Generally, an optical waveguide formed by diffusing a metal element has a problem that the light propagation loss increases due to the diffusion element, and a very good light propagation loss cannot be obtained.

Glass or quartz optical waveguide elements are formed on various substrates such as dielectrics, glass and semiconductors by thin film technology such as sputtering method, vacuum deposition method, chemical vapor deposition method, flame deposition method and sol-gel method. In the structure formed and the manufacturing method, there are some common problems in thin film technology.

First, when a glass or quartz material is used for the optical waveguide portion, generally, the higher the purity and the denser the material, the smaller the light propagation loss, which is preferable.
In the above-mentioned thin film technology, it is generally difficult to control the film quality and the refractive index, and it is difficult to form a high quality film with a small light propagation loss.

Secondly, in the case of connecting an optical waveguide and an optical fiber, the closer the shape and the refractive index are to each other, the smaller the coupling loss can be. However, since the core diameter of the single mode optical fiber is about 10 μm, the thickness is 10 μm by thin film technology. It is difficult to form a uniform film thickness with good film quality. The refractive index of the film formed by the thin film technology does not always match the refractive index of the core part of the optical fiber of the same composition formed by the conventional glass technology (method of melting and solidifying), so the refractive index of the optical fiber should be matched. It is difficult. Also,
Forming a thick film by thin film technology is low in productivity. Furthermore,
Since the materials that can be used as raw materials for thin film technology are extremely limited, there are problems such as low flexibility in function and design.

In the method using the Si thermal oxide film on the Si substrate, the oxide film formation rate is 0.1 μm at 1000 ° C.
Since it is about / hour, it takes a long time to form a thick film, and there is a problem that productivity is low.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce optical propagation loss.
An object of the present invention is to provide an optical waveguide device which has a small coupling loss with an optical fiber and can be integrated with other optical devices and electronic devices, and a manufacturing method thereof.

[0015]

An optical waveguide device according to the present invention comprises a holding substrate and a glass substrate bonded to the holding substrate by direct bonding, the glass substrate having an optical waveguide therein. The above object is achieved. The holding substrate may be a dielectric substrate. In one embodiment,
The dielectric substrate is a dielectric substrate having an electro-optical effect. In another embodiment, the dielectric substrate is lithium niobate or lithium tantalate. Moreover, in one embodiment, the holding substrate is a glass substrate.

The holding substrate may be a semiconductor substrate. In one embodiment, the semiconductor substrate is a silicon substrate. In another embodiment, the semiconductor substrate is a Group 3-5 compound semiconductor substrate. In one embodiment, the semiconductor substrate is a GaAs substrate. The semiconductor substrate may be an InP substrate.

The optical waveguide device according to the present invention has a thin film layer on the surface of at least one of the holding substrate and the glass substrate, and the thin film layer and the other substrate are directly joined to each other. It may have an optical waveguide. In one embodiment, the holding substrate is a dielectric substrate. Further, the dielectric substrate may be a dielectric substrate having an electro-optical effect. In one embodiment, the dielectric substrate is lithium niobate or lithium tantalate. In another embodiment, the holding substrate is a glass substrate.

The holding substrate may be a semiconductor substrate. In one embodiment, the semiconductor substrate is a silicon substrate. In another embodiment, the semiconductor substrate is a Group 3-5 compound semiconductor substrate. In one embodiment, the semiconductor substrate is a GaAs substrate. The semiconductor substrate may be an InP substrate.

The thin film layer may be a silicon layer. Further, the thin film layer may be a silicon compound layer. In one embodiment, the silicon compound layer is a silicon oxide layer. In another embodiment, the silicon compound layer is a silicon nitride layer. In one embodiment, the refractive index of the thin film layer is smaller than that of the glass substrate. In another embodiment, the silicon layer is an amorphous silicon layer. Further, the silicon layer may be a polycrystalline silicon layer.

Another optical waveguide device according to the present invention has a layer having a refractive index lower than that of the glass substrate on the surface of the glass substrate, and the low refractive index layer and the holding substrate are directly bonded to each other. good. Further, the holding substrate and the optical waveguide in the glass substrate may be optically coupled. In one embodiment, the optical coupling between the holding substrate and the optical waveguide in the glass substrate is performed by an optical directional coupler formed by the optical waveguide section in the glass substrate and the optical waveguide section in the holding substrate. . In another embodiment, the optical coupling between the holding substrate and the optical waveguide in the glass substrate is performed by using an end face reflection section provided in the optical waveguide section in the glass substrate.

Another optical waveguide device according to the present invention is
An optical element may be formed in the holding substrate. In one embodiment, an electronic device and / or an optical device is formed in the semiconductor substrate. In one embodiment, the glass substrate used as the holding substrate has a refractive index smaller than that of the glass substrate having the optical waveguide, so that the glass substrate portion having the optical waveguide is provided with the optical waveguide. Are formed.

The method of manufacturing an optical waveguide device according to the present invention is
A step of supplying a glass substrate having first and second surfaces facing each other and a holding substrate having first and second surfaces facing each other, and the first surface of the holding substrate and the second glass substrate of the glass substrate. A step of subjecting at least one of the surfaces to a hydrophilic treatment, the first surface of the holding substrate and the second surface of the glass substrate.
The surface of the substrate is superposed, the holding substrate and the glass substrate that are superposed are subjected to heat treatment, the glass substrate is thinned, and the thinned glass substrate is exposed to light. Forming a waveguide, whereby the above object is achieved. The method may further include a step of forming a thin film layer on at least one of the first surface of the holding substrate and the second surface of the glass substrate. In one embodiment, the thin film layer is a silicon layer or a silicon compound layer.

[0023]

The present invention has been accomplished as a result of intensive research on a method of joining a holding substrate such as a dielectric substrate, a semiconductor substrate or a glass substrate to a glass substrate capable of forming an optical waveguide. The present inventor can obtain a bond having practically sufficient strength by generating hydroxyl groups having a sufficient density on a substrate surface of an inorganic material such as a dielectric substrate, a semiconductor substrate or a glass substrate, and superposing them on each other and heat-treating them. Found out.

That is, when the surface of the inorganic substrate is hydrophilized by an appropriate method, hydroxyl groups are generated on the inorganic surface.
When the inorganic surfaces having surface hydroxyl groups are faced and superposed, the two substrates are joined by hydrogen bonds between the hydroxyl groups. Further, by heat treatment, dehydration condensation occurs between the hydroxyl groups bonded with hydrogen, covalent bonds are formed, and the bonding strength is increased.

Since the bonding method of the present invention does not require a material such as an adhesive for bonding, the optical waveguide device can be formed with high dimensional accuracy. Furthermore, by optimizing the method of hydrophilic treatment or the method of heat treatment, substrates made of various materials and glass substrates can be bonded,
It becomes possible to integrally integrate the optical waveguide element and the optical element or the electronic element.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 FIG. 1 shows a first example of the structure of the optical waveguide device of the present invention. The optical waveguide device of this example is
A holding substrate 1 and a glass substrate 2 are provided. The glass substrate 2 has an optical waveguide portion 3 in a part thereof. The low refractive index layer 4, which is a glass layer or a thin film layer having a refractive index lower than that of the glass substrate 2, is previously formed on the surface of the glass substrate 2. The low refractive index layer 4 can be formed using a conventional thin film technique. The holding substrate 1 and the low refractive index layer 4 are joined by direct joining.

Here, the direct joining will be described using the model shown in FIG. When the surface of the substrate is made extremely clean, and the surface is hydrophilized and immersed in pure water, a large number of hydroxyl groups are generated on the surface of the substrate (FIG. 2A). Surface hydroxyl groups generally have a large dipole moment. When the substrates are stacked on each other in this state, the substrates are firmly bonded to each other by hydrogen bond through the hydroxyl group. Water molecules adsorbed on the surface hydroxyl groups may intervene in this junction. The density of the surface hydroxyl groups generated by the hydrophilic treatment, the amount of adsorbed water, and the magnitude of the dipole moment of the surface hydroxyl groups depend on the material.

When heated in this state, the adsorbed water is gradually dehydrated from the bonding interface (FIG. 2 (b)). When the temperature is further increased, dehydration condensation between hydroxyl groups forming hydrogen bonds proceeds, covalent bonds are formed, and the bond is strengthened. The temperature at which adsorbed water desorbs and the temperature at which hydroxyl groups condense depend on the magnitude of the dipole moment of the surface hydroxyl groups and so on, and therefore differ depending on the material. Further, it is considered that the states shown in FIG. 2 may be mixed.

As mentioned above, the strength of the direct bond depends on the material. As a result of diligent research on the direct bonding method for various materials, after cleaning the substrate surface, applying an appropriate hydrophilizing treatment, immersing it in pure water, and overlaying the substrates with the hydrophilized surfaces facing each other It has been found that, by performing an appropriate heat treatment, it is possible to obtain practically sufficient bonding strength for various dielectrics and semiconductor substrates. Further, the hydrophilic treatment may be applied to either one of the surfaces to be joined. The glass substrate contains a silicon element, and the silicon element forms a bond having a strong covalent bond, so that the bonding strength is stronger than in the case of using other materials. When heat treatment is performed at 300 ° C. for about 1 hour, a bonding strength of several tens of kg / cm ² can be obtained with good reproducibility.

As a result of observing the bonding interface with a TEM (transmission electron microscope), it was found that bonding was performed at the atomic level. Further, no light scattering was observed at the bonding interface.

The above-mentioned bonding is called direct bonding because the bonding interface is bonded at the atomic level and no special material is interposed in the bonding interface for bonding.

The optical waveguide portion 3 which is a part of the glass substrate 2 is slightly thicker than the other portions, and the effective refractive index is increased thereby, so that light is confined in this portion and functions as an optical waveguide. .

Lithium niobate or lithium tantalate, which is a dielectric having an electro-optic effect, is applied to the holding substrate 1.
The glass substrate 2 is made of high-purity silica glass having a refractive index of about 1.45 in the wavelength band of 1.5 μm, and the low refractive index layer 4 has a refractive index of about 1.4.
Of low refractive index glass, silicon oxide or silicon nitride formed by sputtering or chemical vapor deposition,
An optical waveguide device was manufactured. The thickness of the holding substrate 1 is 450μ
m, the thickness of the optical waveguide portion 3 is 10 μm, the thickness of the glass substrate 2 other than the optical waveguide portion is 4 μm, and the thickness of the low refractive index layer 4 is 2 μm.
μm. The light propagation loss of the obtained optical waveguide element is
It was 0.05 dB / cm or less. Also, the core diameter is 10 μm
The coupling loss with the optical fiber was evaluated using the single mode optical fiber of. As a result, the good result that the coupling loss with the optical fiber was 0.5 dB or less was easily obtained.

When bonding is performed using an adhesive instead of using direct bonding, it is difficult to control the thickness of the adhesive with high accuracy, so that the parallelism of the substrates after bonding is deteriorated and the glass or dielectric substrate is deteriorated. Processing accuracy is reduced. Further, since the adhesive made of an organic material has low heat resistance and chemical resistance, the processing process of the glass or the dielectric substrate after bonding is restricted. If the direct bonding of the present invention is used, the above problems do not occur, and the optical waveguide device manufactured by using the direct bonding has excellent reliability.

Example 2 A second example of the structure of the optical waveguide device of the present invention is shown in FIG. In FIG. 3, each component 1
4 to 4 have the same names and functions as those in the first embodiment. In the present embodiment, in addition to the structure of the first embodiment, an amorphous or polycrystalline silicon layer 5 is formed on the surface of the holding substrate 1.
Silicon layer 5 can be formed by conventional thin film techniques.
The silicon layer 5 and the low refractive index layer 4 are joined by direct joining.

The materials and dimensions of each of the constituent elements 1 to 4 are the same as in Example 1, and the amorphous or polycrystalline silicon layer 5 having a thickness of 0.5 μm is formed on the holding substrate 1 to form The optical waveguide device of the example was manufactured. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 3) FIG. 4 shows a third example of the structure of the optical waveguide device of the present invention. In FIG. 4, each component 1
4 to 4 have the same names and functions as those in the first embodiment. In this embodiment, in addition to the structure of the first embodiment, a silicon compound layer 6 of silicon oxide or silicon nitride is formed on the surface of the holding substrate 1. The silicon compound layer 6 can be formed by a conventional thin film technique. The low refractive index layer 4 and the silicon compound layer 6 are
It is joined by direct joining.

The materials and dimensions of the respective constituent elements 1 to 4 are the same as those in the first embodiment, and by forming a silicon oxide or silicon nitride layer having a thickness of 0.5 μm on the holding substrate 1, the optical components of the present embodiment can be obtained. A waveguide element was manufactured. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 4) FIG. 5 shows a fourth example of the structure of the optical waveguide device of the present invention. In FIG. 5, each component 2
4 to 4 have the same names and functions as those in the first embodiment. In this embodiment, the Si substrate 11 which is a semiconductor is used as the holding substrate. The Si substrate 11 and the low refractive index layer 4 are joined by direct joining.

The materials and dimensions of the respective constituent elements 2 to 4 are the same as in Example 1, and the holding substrate is made of S having a thickness of 450 μm.
The optical waveguide device of this example was manufactured by using the i substrate. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

Example 5 FIG. 6 shows a fifth example of the structure of the optical waveguide device of the present invention. In the figure, the names and functions of the components 2 to 4 and 11 are the same as in the fourth embodiment. In this embodiment, in addition to the structure of the fourth embodiment, an amorphous or polycrystalline silicon layer 5 is formed on the surface of the Si substrate 11. The silicon layer 5 and the low refractive index layer 4 are joined by direct joining.

The materials and dimensions of each of the constituent elements 2 to 4 and 11 are the same as in Example 4, and an amorphous silicon layer or a polycrystalline silicon layer having a thickness of 0.5 μm is formed on the surface of the Si substrate 11. Thus, the optical waveguide device of this example was manufactured.
The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

Example 6 FIG. 7 shows a sixth example of the structure of the optical waveguide device of the present invention. In FIG. 7, each component 2
The functions and names of 4 to 11 are the same as those in the fourth embodiment. In this embodiment, in addition to the structure of the fourth embodiment, the silicon compound layer 6 that is a silicon oxide or silicon nitride layer is
It is formed on the surface of the i substrate 11. The silicon compound layer 6 and the low refractive index layer 4 are joined by direct joining.

The materials and dimensions of the respective constituent elements 2 to 4 and 11 are the same as in Example 4, and a silicon oxide layer or a silicon nitride layer having a thickness of 0.5 μm is formed on the surface of the Si substrate 11, The optical waveguide device of this example was manufactured. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 7) FIG. 8 shows a seventh example of the structure of the optical waveguide device of the present invention. In FIG. 8, each component 2
The functions and names of the respective constituent elements 1 to 4 are the same as those in the first embodiment. In this embodiment, a GaAs or InP substrate 12, which is a compound semiconductor of Group 3-5 obtained by combining elements of Groups 3 and 5 of the periodic table, is used as the holding substrate. GaA
The s or InP substrate 12 and the low refractive index layer 4 are directly joined to each other.

The materials and dimensions of the respective constituent elements 2 to 4 are the same as those in the first embodiment, and a 450 μm thick G substrate is used as the holding substrate.
The optical waveguide device of this example was manufactured by using an aAs or InP substrate. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 8) FIG. 9 shows an eighth example of the structure of the optical waveguide device of the present invention. In FIG. 9, each component 2
The names and functions of 4 to 12 are the same as those of the seventh embodiment. In this embodiment, in addition to the configuration of the seventh embodiment, G
An amorphous or polycrystalline silicon layer 5 is formed on the surface of the aAs or InP substrate 12. The silicon layer 5 and the low refractive index layer 4 are joined by direct joining.

The materials and dimensions of the respective constituent elements 2 to 4 and 12 are the same as in Example 7, and an amorphous silicon layer or polycrystalline silicon layer having a thickness of 0.5 μm is formed on the surface of the GaAs or InP substrate 12. By forming it, the optical waveguide device of this example was manufactured. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 9) FIG. 10 shows a ninth example of the structure of the optical waveguide device of the present invention. In FIG. 10, the names and functions of the components 2 to 4 and 12 are the same as in the seventh embodiment. In this embodiment, in addition to the configuration of the seventh embodiment,
A silicon compound layer 6 which is a silicon oxide or silicon nitride layer is formed on the surface of a GaAs or InP substrate 12.
The silicon compound layer 6 and the low refractive index layer 4 are joined by direct joining.

The materials and dimensions of each of the constituent elements 2 to 4 and 12 are the same as in Example 7, and a silicon oxide layer or silicon nitride layer having a thickness of 0.5 μm is formed on the GaAs or InP substrate 12.
An optical waveguide device of this example was manufactured by forming the optical waveguide device on the surface. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1.
As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 10) FIG. 11 shows a tenth example of the structure of the optical waveguide device of the present invention. In FIG. 11, the names and functions of the components 2 to 4 are the same as in the first embodiment. In this embodiment, the glass substrate 13 is used as the holding substrate. The holding glass substrate 13 and the low refractive index layer 4 are joined by direct joining.

The materials and dimensions of each of the constituent elements 2 to 4 are the same as those in the first embodiment, and the thickness of the holding substrate is 450 μm.
An optical waveguide device of this example was manufactured by using a high-purity silica glass substrate having a refractive index of about 1.45 in the wavelength band of 1.5 μm. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 11) An eleventh example of the structure of the optical waveguide device of the present invention is shown in FIG. In FIG. 12, the names and functions of the components 2 to 4 and 13 are the same as in the tenth embodiment. In this embodiment, in addition to the structure of the tenth embodiment, an amorphous or polycrystalline silicon layer 5 is formed on the surface of the holding glass substrate 13. The silicon layer 5 and the low refractive index layer 4 are joined by direct joining.

The materials and dimensions of each of the constituent elements 2 to 4 and 13 are the same as in Example 10, and an amorphous silicon layer or a polycrystalline silicon layer having a thickness of 0.5 μm is formed on the surface of the holding glass substrate. By doing so, the optical waveguide device of this example was manufactured. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 12) A twelfth example of the structure of the optical waveguide device of the present invention is shown in FIG. In FIG. 13, the functions and names of the components 2 to 4 and 13 are the same as in the tenth embodiment. In this embodiment, in addition to the structure of the tenth embodiment, a silicon compound layer 6 which is a silicon oxide or silicon nitride layer is formed on the surface of the holding glass substrate 13.
The silicon compound layer 6 is joined by direct joining.

The materials and dimensions of each of the constituent elements 2 to 4 and 13 are the same as in Example 10, and a silicon oxide or silicon nitride layer having a thickness of 0.5 μm is formed on the surface of the holding glass substrate. The optical waveguide device of this example was manufactured.
The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 13) A thirteenth example of the structure of the optical waveguide device of the present invention is shown in FIG. In FIG. 14, the names and functions of the components 2 and 3 are the same as in the first embodiment.
In this embodiment, a glass substrate is used as the holding substrate, and the refractive index of the holding glass substrate 14 is smaller than that of the optical waveguide glass substrate 2. Therefore, in this embodiment,
There is no low refractive index layer 4 of Example 1. Holding glass substrate 14
The optical substrate glass substrate 2 and the optical waveguide glass substrate 2 are directly joined to each other.

In this embodiment, a high-purity quartz glass having a refractive index of 1.40 in the wavelength band of 1.5 μm and a refractive index of about 1.45 in the wavelength band of 1.5 μm is used for the holding glass substrate 14 and the glass substrate 2. The optical waveguide device of Holding glass substrate 14
Is 450 μm, the thickness of the optical waveguide part 3 is 10 μm,
The thickness of the glass substrate 2 other than the optical waveguide portion was 4 μm. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Embodiment 14) FIG. 15 shows a fourteenth example of the structure of the optical waveguide device of the present invention. In FIG. 15, the names and functions of the respective constituent elements 2, 3, and 14 are the same as in the thirteenth embodiment. In the present embodiment, in addition to the structure of the thirteenth embodiment, an amorphous or polycrystalline silicon layer 5 is formed on the surface of the holding glass substrate 14. The optical waveguide glass substrate 2 and the amorphous silicon or polycrystalline silicon layer 5 are directly joined to each other.

The materials and dimensions of the respective constituent elements 2, 3 and 14 were the same as in Example 13, and an amorphous silicon layer or polycrystalline silicon layer having a thickness of 0.5 μm was formed on the surface of the glass substrate 14 for holding. By forming it, the optical waveguide device of this example was manufactured. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

Example 15 FIG. 16 shows a fifteenth example of the structure of the optical waveguide device of the present invention. In FIG. 16, the names and functions of the constituent elements 2, 3, and 14 are the same as in the thirteenth embodiment. In this embodiment, in addition to the structure of the thirteenth embodiment, a silicon compound layer 6 which is a silicon oxide or silicon nitride layer is formed on the surface of the holding glass substrate 14. The glass substrate 2 for optical waveguide and the silicon compound layer 6 are joined by direct joining.

The materials and dimensions of the respective constituent elements 2, 3 and 14 are the same as in Example 13, and a 0.5 μm thick silicon oxide layer or silicon nitride layer is formed on the surface of the holding glass substrate 14. Thus, the optical waveguide device of this example was manufactured. The optical propagation loss of the obtained optical waveguide device and the coupling loss with the optical fiber were evaluated in the same manner as in Example 1. As a result, good results almost similar to those in Example 1 were obtained.

(Example 16) A sixteenth example of the structure of the optical waveguide device of the present invention is shown in FIG. FIG. 17 illustrates a cross-sectional structure of the optical waveguide portion provided on the glass substrate.
In FIG. 17, a lithium niobate or lithium tantalate substrate 21, which is a dielectric substrate having an electro-optical effect, is used as the holding substrate. Optical waveguide sections 22 and 23 are provided on a glass substrate. The optical waveguide portions 22 and 23 correspond to the optical waveguide portion 3 of the first embodiment. Low refractive index layers 24, 25
Is a glass or thin film layer having a refractive index lower than that of the optical waveguide portions 22 and 23. Low refractive index layer 24,
25 can be made by conventional thin film technology. Optical fiber 2
Reference numerals 6 and 27 are connected to the glass optical waveguide portions 22 and 23. An optical element 28 utilizing an electro-optical effect, such as an optical waveguide type optical modulator, is formed on the dielectric substrate 21. The optical waveguides 29 and 30 are the glass substrate optical waveguide portions 22 and 23.
And the low-refractive-index layers 24 and 25, so as to form an optical waveguide type optical directional coupler. Optical waveguide 2
9 and 30 can be formed on the dielectric substrate 21 by a conventional thin film technique. The low refractive index layers 24 and 25 and the optical waveguides 29 and 30 are directly joined to each other.

Next, the operation and function of the element having the structure of this embodiment will be described. The signal light propagated from the outside guided by the optical fiber 26 is coupled to the glass substrate optical waveguide portion 22 with a small coupling loss. The optical signal that has entered this optical waveguide portion is guided to the optical directional coupler formed below it. The optical directional coupler is provided with two optical waveguides arranged in parallel, the distance between the waveguides (direction perpendicular to the light propagation direction), the length of the optical waveguide (light propagation direction), the width of the optical waveguide (light propagation direction). Propagation in one of the optical waveguides when propagating light for a certain distance by making the thickness of the optical waveguide (vertical direction parallel to the substrate) and the optical waveguide thickness (perpendicular to the substrate) appropriate values. It is an optical element that can transfer almost all the light energy therein to the other optical waveguide provided in parallel. The shape, size and refractive index of the glass substrate optical waveguide portion 22, the low refractive index layer 24 therebelow and the optical waveguide 29 on the dielectric substrate are appropriately set so that all the light energy entering the glass substrate optical waveguide portion 22 is obtained. An optical directional coupler is formed so as to move to the optical waveguide 29. Therefore, the light that has entered from the optical fiber 26 has an extremely small loss, and the optical waveguide 29
Move on to. The optical waveguide 29 is connected to an optical element 28 such as an optical modulator and can perform processing such as optical modulation.
The light emitted from the optical element 28 enters the optical waveguide 30. The optical waveguide 30 includes the glass substrate optical waveguide portion 2 provided on the upper portion thereof.
3 and the optical directional coupler.
The light energy propagating through the optical waveguide 30 is transferred to the glass substrate optical waveguide portion 23 by this optical directional coupler, is coupled to the connected optical fiber 27 with low loss, and is guided to the outside.

With this structure, the optical waveguide on the glass substrate and the dielectric substrate having the optical element utilizing the electro-optical effect can be optically coupled to each other, and the optical waveguide and the optical device having a high function can be combined. The device and the device can be integrated. Since the glass substrate optical waveguide part easily matches its shape, size, and refractive index with the optical fiber, the coupling loss with the optical fiber is coupled to the optical waveguide formed of a material having a large refractive index such as lithium niobate or lithium tantalate. It can be much smaller than the case. Further, the glass optical waveguide can make the optical propagation loss much smaller than that of the dielectric optical waveguide. Therefore, with such a configuration, the optical waveguide with less propagation loss and coupling loss with the optical fiber and the dielectric optical element utilizing the electro-optical effect can be efficiently integrated. Further, by using the direct bonding according to the present invention, the above configuration can be realized with a processing accuracy accuracy of a fraction of a wavelength or less.

(Embodiment 17) FIG. 18 shows a seventeenth example of the structure of the optical waveguide device of the present invention. FIG. 18 illustrates a cross-sectional structure of the optical waveguide section. In FIG. 18, the holding Si substrate 11, the optical waveguide portion 3, and the low refractive index layer 4 have the same configurations as those in the fourth embodiment. The Si substrate 11 and the low refractive index layer 4 are joined by direct joining. In this embodiment, the end face reflection portion 31 is provided at the end portion of the optical waveguide portion 3. In addition, the photodiode 32 as an optical element is S
It is formed on the i substrate. The optical fiber 33 is connected to the optical waveguide section 3.

The signal light propagated from the outside guided by the optical fiber 33 is coupled to the optical waveguide portion 3 with a small coupling loss. The optical signal that has entered the optical waveguide portion 3 is reflected by the end face reflection portion 31 formed in a part thereof and enters the Si substrate. If, for example, a photodiode is formed as an optical element on the Si substrate where light is incident, an optical signal entering the optical waveguide can be converted into an electrical signal. With such a configuration, the optical waveguide on the glass substrate and the optical element on the Si semiconductor substrate can be optically coupled, and the optical waveguide and the optical element having a high function can be integrated. Although not specifically shown in FIG. 18, it is possible to form electronic elements such as various transistors on other portions of the Si substrate, for example, to have a function of amplifying a signal converted from light to electricity. With such a structure, the optical waveguide and the Si semiconductor optoelectronic circuit with less propagation loss and coupling loss with the optical fiber can be integrated efficiently and integrally.

(Embodiment 18) FIG. 19 shows an eighteenth example of the structure of the optical waveguide device of the present invention. FIG. 19 is a diagram showing a cross-sectional structure of the optical waveguide portion. In FIG. 19, GaA
The s or InP substrate 12, the optical waveguide portion 3, and the low refractive index layer 4 have the same configurations as in the seventh embodiment. GaAs or I
The nP substrate 12 and the low refractive index layer 4 are joined by direct joining. In this embodiment, the end face reflection portion 31 is
It is provided at the end of the optical waveguide section 3. Further, a surface emitting semiconductor laser 34 is formed on the GaAs or InP substrate 12 as an optical element. The optical fiber 33 is connected to the optical waveguide section 3.

The optical signal generated by the light emission of the surface-emitting type semiconductor laser 34 is reflected to the optical waveguide portion 3 side by the end face reflection portion 31 of the optical waveguide portion 3 and is connected to the optical waveguide portion 3 with low loss. It is transmitted to the outside by 33. With such a configuration, the optical waveguide on the glass substrate and the GaAs or InP semiconductor substrate can be optically coupled, and the optical waveguide and the optical element having a high function can be integrated. Although not shown in the figure,
For example, it is possible to form an electronic element such as various transistors on another portion of the GaAs or InP substrate to have a function of driving the surface emitting semiconductor laser.
With such a structure, an optical waveguide with less propagation loss and coupling loss between the optical fiber and GaAs or In
The P semiconductor optoelectronic circuit can be integrated efficiently and integrally.

(Example 19) FIG. 20 shows a nineteenth example of the structure of the optical waveguide element of the present invention. FIG. 20 is a diagram showing a structure of a cross section of the optical waveguide portion provided on the glass substrate along the optical waveguide. First glass substrate 41 which is a holding substrate
The optical waveguide portion 42 is provided on the second glass substrate above the substrate. The low refractive index layer 43 having a lower refractive index than the second glass substrate is provided on the second glass substrate. An optical waveguide 44 is provided on the back surface of the first glass substrate that is the holding substrate. The end surface reflection portion 45 provided at the end portion of the optical waveguide portion 42 and the end surface reflection portion 46 provided at the end portion of the optical waveguide 44 are provided so as to face each other. An optical fiber 47 is connected to the optical waveguide section 42. The first glass substrate 41, which is a holding substrate, and the low-refractive index layer 43 provided on the optical waveguide portion 42 are joined by direct joining.

The signal light propagated from the outside guided by the optical fiber 47 is coupled to the optical waveguide portion 42 with a small coupling loss. The optical signal that has entered the optical waveguide portion 42 is optically coupled to the optical waveguide 44 through the end face reflection portions 45 and 46 with a very small loss.

The optical waveguide 44 on the glass substrate 41, which is a holding substrate, may be formed in advance by using a conventional method such as Ti diffusion. The end face reflection part is processed by polishing or the like before bonding so as to have an inclined surface most suitable for reflection, for example, an inclined surface of 45 degrees, and the optical signal to be propagated is totally reflected at an angle of 45 degrees. It can be realized by forming an optical reflection film on the.

With this structure, an optical signal can be transmitted to the optical waveguide provided on the other surface of the substrate. That is, high-level functions can be integrated in the optical waveguide device.

(Embodiment 20) FIG. 21 shows a twentieth example of the structure of the optical waveguide element of the present invention. In FIG. 21, the names and functions of the components 2 to 4 are the same as in the first embodiment. As the material of the holding substrate 51, as described in the above-mentioned embodiments, the dielectric material such as lithium niobate, lithium tantalate, glass or semiconductor may be used. In this embodiment, the entire upper surface of the glass substrate 2 including the optical waveguide portion,
A layer (clad layer) 52 having a refractive index lower than that of the optical waveguide portion is formed. The cladding layer 52 is specifically a film of silicon oxide, silicon nitride, or the like, and can be easily formed by a chemical vapor deposition method or the like.

With such a structure, a symmetrical structure having low refractive index layers above and below the optical waveguide portion can be achieved, so that light confinement can be made more effective and coupling with an optical fiber is easier. Becomes

(Embodiment 21) A first example of a method for manufacturing an optical waveguide device according to the present invention will be described with reference to the manufacturing process chart shown in FIG.

First, after the portion of the surface of the holding substrate to be joined is extremely cleaned, it is hydrophilized. When the holding substrate is a dielectric such as lithium niobate or lithium tantalate, a glass substrate, a Si semiconductor substrate, etc., the surface of the holding substrate is slightly removed by etching with a hydrofluoric acid-based etching solution, and then the ammonia-peroxide is used. The surface can be made hydrophilic by immersing it in a hydrogen oxide-based solution. When the semiconductor substrate is GaAs or InP-based, the surface can be made hydrophilic by slightly removing the surface with a sulfuric acid-hydrogen peroxide-based etching solution and then performing the same treatment. Then, the holding substrate is immersed in pure water and washed. By performing the hydrophilic treatment in this manner, hydroxyl groups are introduced into the surface of the holding substrate, and a highly hydrophilic surface having water molecules adsorbed is obtained.

On the other hand, for the glass substrate for the optical waveguide, a glass layer, a silicon oxide layer or a silicon nitride layer having a refractive index lower than that of the substrate constituent material is formed by a method such as chemical vapor deposition if necessary. After that, the surface is cleaned and then a hydrophilic treatment is applied. The hydrophilic treatment method is almost the same as that of the holding substrate.

When the surfaces of the holding substrate and the glass substrate for an optical waveguide to be joined are made hydrophilic and superposed in this manner, they are directly joined by hydrogen bonds between the hydroxyl groups and adsorbed water molecules. By performing heat treatment in this state, water molecules adsorbed from the bonding interface are gradually desorbed, hydrogen bonds between surface hydroxyl groups and dehydration condensation between hydrogen bonded hydroxyl groups form covalent bonds, and the strength of direct bonding is increased. To rise. Since the strength of direct bonding depends on the materials, in some cases, practically sufficient bonding strength can be obtained only by subjecting one surface of the substrates to be bonded to hydrophilic treatment. In addition, there is a material system that can obtain practically sufficient bonding strength without heat treatment.

After the direct bonding, the glass substrate for an optical waveguide can be thinned to a predetermined thickness by a method such as polishing, cutting and etching.

Subsequently, an optical waveguide is formed. The method of forming the optical waveguide includes a method of making the optical waveguide portion thicker than the other portion by etching, and a method of diffusing a substance that increases the refractive index into the optical waveguide portion to make the optical waveguide portion have a higher refractive index than the other portions. There is a way to raise it. In the case of the former method, a so-called ridge-type optical waveguide is formed by forming a resist mask on the portion where the optical waveguide is formed by a photolithography technique and etching the other portion to be thinner than the optical waveguide portion. be able to. In the latter case, a layer of metal such as Ti is formed on the portion where the optical waveguide is formed by vacuum vapor deposition and photolithography, and then Ti is diffused by heat treatment at a high temperature to change the refractive index of the diffusion portion to other values. The optical waveguide is formed by increasing the height of the optical waveguide. Various optical waveguide elements can be formed by processing the optical waveguide into a shape suitable for each purpose.

The typical shape, size and refractive index of each portion are as described in the first embodiment. The initial thickness of the glass substrate is preferably such that it has a handleable strength and can be easily processed into a thin plate, and is usually about 100 to 1000 μm.

The heat treatment temperature for strengthening the bond is 100 ° C.
With the above effects, the glass substrate can be heated to a high temperature within a range not exceeding the softening point. If the thermal expansion coefficients of the holding substrate and the glass substrate are matched, it is possible to achieve temperatures up to about 1000 ° C. by using a material having a high softening temperature and a high melting point. In addition, by applying a high electric field to the bonding interface during the heat treatment, the bonding strength can be improved at a lower temperature.

When the bonding is performed by such a method, extremely good substrate flatness can be obtained. Therefore, when performing thinning processing,
The thickness of each part can be easily controlled with high accuracy. Further, since the degree of freedom in selecting the glass substrate material is large, the optical waveguide device having low propagation loss and low coupling loss as described in the embodiment can be obtained. Furthermore, compared with the method of forming the optical waveguide part by thin film technology, the optical waveguide part can be formed by using a bulk material, so that it is possible to obtain a product with excellent characteristics and manufacturing reproducibility, and it is also suitable for mass production. .

(Embodiment 22) A second example of the method for manufacturing an optical waveguide device of the present invention will be described.

First, a series of electronic element or optical element forming process treatments including a process, such as a diffusion process, which needs to be performed at a predetermined temperature of the holding substrate at a heat treatment temperature for direct bonding to be performed later, for example, a diffusion process or the like. Then, electronic elements such as photodiodes and optical elements such as optical modulators and optical waveguides are formed.

Next, a silicon or silicon compound film is formed on the bonded portion of the surface of the holding substrate. The silicon film may be polycrystalline or amorphous. The silicon compound film may be silicon oxide, silicon nitride or the like. Any of these films can be formed by chemical vapor deposition or sputtering. The film thickness is 0.5
It is about μm. After this, as in Example 21, the portion to be joined on the surface of the silicon or silicon compound film is extremely cleaned,
Hydrophilize. Thereafter, by using the same process as in Example 21, optical waveguide elements having the structures shown in Examples 2, 3 and the like are obtained.

(Example 23) A third example of the method for manufacturing an optical waveguide device of the present invention will be described.

In the manufacturing method of Example 21, the end face of the glass substrate having the low refractive index layer is preliminarily processed to form the end face reflection portion. For example, it can be processed into an appropriate angle by polishing. Further, an antireflection film that selectively reflects light having a wavelength to be propagated to the optical waveguide and prevents reflection of light having another wavelength is formed on this surface by vacuum vapor deposition or the like. Then, the end face reflection portion is arranged at a predetermined position of the semiconductor substrate to be joined, for example, on the photodiode, and the direct joining and the formation of the optical waveguide portion are performed by the same method as in the twenty-first embodiment. This gives Examples 17, 18 and 1
It is possible to obtain an element having the structure described in 9 in which the optical waveguide portion and the optical element on the holding substrate are optically coupled.

The angle of oblique polishing is, for example, 45 degrees, and the antireflection film may be, for example, a silicon oxide-titanium oxide multilayer film.

Although GaAs or InP is used as the 3-5 group compound semiconductor in the above embodiment, other 3-5 group compound semiconductors such as AlGaAs and InGaAsP have very similar surface chemistries. The structure and manufacturing method of this embodiment can be applied in the same manner.

The dimensions of the respective portions shown in the embodiments are representative examples, and the dimensions are not limited to these.

Further, in the embodiment, the structure of the glass optical waveguide is shown as a so-called ridge type optical waveguide structure in which the thickness of the optical waveguide portion is thicker than other portions, but an ion diffusion type optical waveguide such as Ti, Other optical waveguide forming techniques such as a proton exchange type optical waveguide may be used.

[0095]

Since the present invention comprises the constitution and manufacturing method as described above, the following effects can be obtained.

On a holding substrate such as a dielectric substrate having an electro-optical effect or a semiconductor substrate having an electronic element or an optical element,
Glass optical waveguides can be integrated together. Since the glass optical waveguide and the optical element formed on the dielectric substrate can be optically connected, it is possible to optically couple the dielectric optical element excellent in response and controllability and the optical fiber with low loss. You can

Further, almost any glass material can be used for the optical waveguide portion. Therefore, by selecting a glass material having a very small light propagation loss, it is possible to obtain an optical waveguide device having a very small light propagation loss. Further, by selecting the glass material, the refractive indexes of the optical waveguide portion and the optical fiber can be matched, so that an optical waveguide element with a small coupling loss with the optical fiber can be obtained.

Furthermore, it is possible to form an optical waveguide portion having a cross-sectional shape close to that of the core portion of the optical fiber. In addition, since a bulk material can be used, the productivity of the optical waveguide device having the thick optical waveguide portion is remarkably high as compared with the manufacturing method using the thin film technology.

Further, since a material such as an adhesive is not used for joining in forming the optical waveguide device, it is possible to perform processing with high dimensional accuracy and obtain an optical waveguide device having excellent characteristics. Furthermore, since no organic material is used, an optical waveguide device having excellent temperature characteristics, environment resistance and reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a model diagram showing the mechanism of direct joining according to the present invention.

FIG. 3 is a configuration diagram of a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 7 is a configuration diagram of a sixth embodiment of the present invention.

FIG. 8 is a configuration diagram of a seventh embodiment of the present invention.

FIG. 9 is a configuration diagram of an eighth embodiment of the present invention.

FIG. 10 is a configuration diagram of a ninth embodiment of the present invention.

FIG. 11 is a configuration diagram of a tenth embodiment of the present invention.

FIG. 12 is a block diagram of an eleventh embodiment of the present invention.

FIG. 13 is a configuration diagram of a twelfth embodiment of the present invention.

FIG. 14 is a configuration diagram of a thirteenth embodiment of the present invention.

FIG. 15 is a configuration diagram of a fourteenth embodiment of the present invention.

FIG. 16 is a configuration diagram of a fifteenth embodiment of the present invention.

FIG. 17 is a configuration diagram of a sixteenth embodiment of the present invention.

FIG. 18 is a configuration diagram of a seventeenth embodiment of the present invention.

FIG. 19 is a configuration diagram of an eighteenth embodiment of the present invention.

FIG. 20 is a configuration diagram of a nineteenth embodiment of the present invention.

FIG. 21 is a configuration diagram of a twentieth embodiment of the present invention.

FIG. 22 is a process drawing of the manufacturing method of the present invention.

[Explanation of symbols]

1 Holding Substrate 2 Glass Substrate 3 Optical Waveguide 4 Low Refractive Index Layer 5 Silicon Layer 6 Silicon Compound Layer 11 Holding Substrate (Si) 12 Holding Substrate (GaAs or InP) 13 Holding Substrate (Glass) 14 Holding Substrate (Low Refractive Index Glass) ) 21 holding substrate (lithium niobate or lithium tantalate) 22, 23 glass substrate optical waveguide part 24, 25 low refractive index layer 26, 27 optical fiber 31 end face reflection part 32 photodiode 33 optical fiber 34 conductor laser 41 holding first Glass substrate 42 Optical waveguide portion 43 Low refractive index layer 44 Optical waveguides 45, 46 provided on a holding substrate End face reflection portion 47 Optical fiber

Claims (42)

[Claims] 1. An optical waveguide device comprising a holding substrate and a glass substrate directly bonded to the holding substrate, the glass substrate having an optical waveguide therein. 2. The optical waveguide device according to claim 1, wherein the holding substrate is a dielectric substrate. 3. The optical waveguide device according to claim 2, wherein the dielectric substrate is a dielectric substrate having an electro-optical effect. 4. The optical waveguide device according to claim 3, wherein the dielectric substrate is lithium niobate or lithium tantalate. 5. The optical waveguide device according to claim 1, wherein the holding substrate is a glass substrate. 6. The optical waveguide device according to claim 1, wherein the holding substrate is a semiconductor substrate. 7. The optical waveguide device according to claim 6, wherein the semiconductor substrate is a silicon substrate. 8. The optical waveguide device according to claim 6, wherein the semiconductor substrate is a 3-5 group compound semiconductor substrate. 9. The optical waveguide device according to claim 8, wherein the semiconductor substrate is a GaAs substrate. 10. The optical waveguide device according to claim 8, wherein the semiconductor substrate is an InP substrate. 11. A holding substrate and a glass substrate are provided, and a thin film layer is provided on a surface of at least one of the holding substrate and the glass substrate, and the holding substrate and the glass substrate are provided through the thin film layer. An optical waveguide element in which the glass substrate and the glass substrate are internally bonded by direct bonding. 12. The optical waveguide device according to claim 11, wherein the holding substrate is a dielectric substrate. 13. The optical waveguide device according to claim 12, wherein the dielectric substrate is a dielectric substrate having an electro-optical effect. 14. The optical waveguide device according to claim 13, wherein the dielectric substrate is lithium niobate or lithium tantalate. 15. The optical waveguide device according to claim 11, wherein the holding substrate is a glass substrate. 16. The optical waveguide device according to claim 11, wherein the holding substrate is a semiconductor substrate. 17. The optical waveguide device according to claim 16, wherein the semiconductor substrate is a silicon substrate. 18. The optical waveguide device according to claim 16, wherein the semiconductor substrate is a Group 3-5 compound semiconductor substrate. 19. The optical waveguide device according to claim 18, wherein the semiconductor substrate is a GaAs substrate. 20. The optical waveguide device according to claim 18, wherein the semiconductor substrate is an InP substrate. 21. The thin film layer is a silicon layer.
The optical waveguide device according to. 22. The optical waveguide device according to claim 11, wherein the thin film layer is a silicon compound layer. 23. The optical waveguide device according to claim 22, wherein the silicon compound layer is a silicon oxide layer. 24. The optical waveguide device according to claim 22, wherein the silicon compound layer is a silicon nitride layer. 25. The optical waveguide device according to claim 22, wherein the refractive index of the thin film layer is smaller than the refractive index of the glass substrate. 26. The optical waveguide device according to claim 21, wherein the silicon layer is an amorphous silicon layer. 27. The optical waveguide device according to claim 21, wherein the silicon layer is a polycrystalline silicon layer. 28. A layer having a refractive index lower than that of the glass substrate is provided on the surface of the glass substrate, and the layer and the holding substrate are directly bonded to each other.
The optical waveguide device according to. 29. A layer having a refractive index lower than that of the glass substrate is provided on the surface of the glass substrate, and the layer and the holding substrate are directly bonded to each other.
1. The optical waveguide device according to 1. 30. The optical waveguide element according to claim 1, wherein the holding substrate and the optical waveguide in the glass substrate are optically coupled. 31. The optical waveguide device according to claim 11, wherein the holding substrate and the optical waveguide in the glass substrate are optically coupled. 32. The optical coupling between the holding substrate and the optical waveguide in the glass substrate is performed by an optical directional coupler formed by the optical waveguide portion in the glass substrate and the optical waveguide portion in the holding substrate. The optical waveguide device according to claim 29. 33. The optical waveguide according to claim 29, wherein the holding substrate and the optical waveguide in the glass substrate are optically coupled by using an end face reflection portion provided in the optical waveguide portion in the glass substrate. element. 34. The optical waveguide element according to claim 1, wherein an optical element is formed in the holding substrate. 35. The optical waveguide device according to claim 11, wherein an optical device is formed in the holding substrate. 36. An electronic device or /
The optical waveguide element according to claim 6, wherein an optical element is formed. 37. An electronic device or / in the semiconductor substrate
The optical waveguide device according to claim 16, wherein an optical device is formed. 38. The optical waveguide element according to claim 5, wherein the glass substrate used as the holding substrate has a refractive index smaller than that of the glass substrate having the optical waveguide. 39. The optical waveguide element according to claim 15, wherein the glass substrate used as the holding substrate has a refractive index smaller than that of the glass substrate having the optical waveguide. 40. A step of supplying a glass substrate having first and second surfaces facing each other and a holding substrate having first and second surfaces facing each other, and the first surface of the holding substrate and the glass. A step of subjecting at least one of the second surface of the substrate to a hydrophilization treatment, and a step of causing the first surface of the holding substrate and the second surface of the glass substrate to face each other and superimposing them on each other; An optical waveguide element including: a step of subjecting the laminated holding substrate and the glass substrate to a heat treatment; a step of thinning the glass substrate; and a step of forming an optical waveguide on the thinned glass substrate. Manufacturing method. 41. Before the step of applying the hydrophilic treatment, the method further includes the step of forming a thin film layer on at least one of the first surface of the holding substrate and the second surface of the glass substrate. The method for manufacturing an optical waveguide device according to claim 40. 42. The method of manufacturing an optical waveguide device according to claim 41, wherein the thin film layer is a silicon layer or a silicon compound layer.